1. Field of the Invention
The present invention relates to a gear roll-forming apparatus capable of roll-forming a bevel gear or a bevel pinion.
2. Description of the Related Art
A conventional gear roll-forming apparatus can enable roll-forming of a large-diameter bevel gear that can mesh with a bevel pinion. In one such arrangement, the first gear roll-forming apparatus includes a pinion die of substantially the same configuration and size as the bevel pinion, a driver that supports the pinion die so that the pinion die can be driven to rotate about its axis, and a support member for supporting an annular bevel gear blank, with which the pinion die can be brought into press contact, so that the bevel gear blank can rotate about its axis.
The pinion die is brought into press contact with the bevel gear blank, and the pinion die is rotated. Then, the bevel gear blank rotates in synchronism with this rotation, causing the teeth of the pinion die to roll with respect to the bevel gear blank. Accordingly, teeth corresponding to the profile of the teeth of the pinion die are roll-formed in the bevel gear blank, that is, the bevel gear is roll-formed.
On the other hand, Japanese Patent Document JP-A-2003-53467 discloses another type of conventional gear roll-forming apparatus that enables roll-forming of the bevel pinion of a small diameter. According to the structure disclosed in this publication, the second gear roll-forming apparatus includes a pair of rack-type flat dies arranged in such a manner that their respective teeth are opposed to each other. The tooth profile of each of these flat dies is made to approximate the tooth profile of the bevel pinion.
While sandwiching the bevel pinion blank between the two flat dies, the two flat dies are moved in opposite directions with respect to the longitudinal direction of the flat dies. This causes the respective teeth of these flat dies to roll relative to the bevel pinion blank, whereby teeth corresponding to the profile of the teeth of the respective flat dies are roll-formed in the bevel pinion blank, that is, the bevel pinion is roll-formed.